This view of the twilight sky and Martian horizon taken by NASA's Curiosity Mars rover includes Earth as the brightest point of light in the night sky. Earth is a little left of center in the image, and our moon is just below Earth.

This frame from an animation from NASA's Mars rover Curiosity shows the rover drilling into rock target 'Cumberland.' The drilling was performed during the 279th Martian day, or sol, of the Curiosity's work on Mars (May 19, 2013).

This image from the Mars Hand Lens Imager on NASA's Mars rover Curiosity shows the patch of rock cleaned by the first use of the rover's Dust Removal Tool (DRT). The tool is a motorized, wire-bristle brush on the turret at the end of the rover's arm.

The two bodies in this portion of an evening-sky view by NASA's Mars rover Curiosity are Earth and Earth's moon. The rover's Mast Camera (Mastcam) imaged them in the twilight sky of Curiosity's 529th Martian day, or sol (Jan. 31, 2014).

This artist concept features NASA's Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars' past or present ability to sustain microbial life. Curiosity is being tested in preparation for launch in the fall of 2011.

This artist concept features NASA's Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars' past or present ability to sustain microbial life. The rover examines a rock on Mars with a set of tools at the end of the rover's arm.

The heat shield for NASA's Mars Science Laboratory is the largest ever built for a planetary mission. This image shows the heat shield being prepared at Lockheed Martin Space Systems, Denver, in April 2011.

Technicians at Lockheed Martin Space Systems, Denver, prepare the heat shield for NASA's Mars Science Laboratory. With a diameter of 4.5 meters (nearly 15 feet), this heat shield is the largest ever built for a planetary mission.

The arm and the remote sensing mast of the Mars rover Curiosity each carry science instruments and other tools for NASA's Mars Science Laboratory mission. This image shows the arm on the left and the mast just right of center.

The rover for NASA's Mars Science Laboratory mission, named Curiosity, is seen here inside the Spacecraft Assembly Facility at NASA's Jet Propulsion Laboratory, Pasadena, Calif. Support equipment is holding the rover slightly off the floor.

The remote sensing mast on NASA's Mars rover Curiosity holds two science instruments for studying the rover's surroundings and two stereo navigation cameras for use in driving the rover and planning rover activities.

The rover for NASA's Mars Science Laboratory mission, named Curiosity, is about 3 meters (10 feet) long, not counting the additional length that the rover's arm can be extended forward. The front of the rover is on the left in this side view.

The Mast Camera (Mastcam) on NASA's Mars rover Curiosity has two rectangular 'eyes' near the top of the rover's remote sensing mast. This image shows Curiosity on a tilt table NASA's Jet Propulsion Laboratory, Pasadena, California.

This image shows preparation for March 2011 testing of the Mars Science Laboratory rover, Curiosity, in a space-simulation chamber; the rover will go through operational sequences in environmental conditions similar to what it will experience on Mars.

This image shows preparation for March 2011 testing of the Mars Science Laboratory rover, Curiosity, in a space-simulation chamber; the rover will go through operational sequences in environmental conditions similar to what it will experience on Mars.

Grad student Nicholas Boyd (left) and Principal Investigator Ralf Gellert, both of the University of Guelph, Ontario, Canada, prepare for the installation of the Alpha Particle X-ray Spectrometer sensor head during testing at NASA's JPL.

NASA's Sample Analysis at Mars (SAM) instrument, largest of the 10 science instruments for NASA's Mars Science Laboratory mission, will examine samples of Martian rocks, soil and atmosphere for information about chemicals that are important to life.

This schematic illustration for NASA's Mars Science Laboratory's Sample Analysis at Mars (SAM) instrument shows major components of the microwave-oven-size instrument, which will examine samples of Martian rocks, soil and atmosphere.

Researchers prepare for a test of the Chemistry and Camera (ChemCam) instrument that will fly on NASA's Mars Science Laboratory mission; researchers are preparing the instrument's mast unit for a laser firing test.

Sensors on two finger-like mini-booms extending horizontally from the mast of NASA's Mars rover Curiosity will monitor wind speed, wind direction and air temperature; image taken during installation of the instrument inside a clean room at NASA's JPL.

This stereo view of terrestrial rocks combines two images taken by a testing twin of the Mars Hand Lens Imager (MAHLI) camera on NASA's Mars Science Laboratory. 3D glasses are necessary to view this image.

The Mars Hand Lens Imager (MAHLI) camera will fly on NASA's Mars Science Laboratory mission, launching in late 2011. This photo of the camera was taken before MAHLI's November 2010 installation onto the robotic arm of the mission's Mars rover, Curiosity.